In a large saucepan combine and heat all ingredients but baking soda and vanilla. Dissolve sugar. Stir in soda and vanilla. Mixture will fizz and double in height (beware, it boils over easily and makes a sticky mess!). Stir occasionally until fizz is gone and syrup is thick and caramel like. Serve hot over Pumpkin Waffles (or ice cream if you have any leftover!).